Underground map vital for subway project: Surjadi

JAKARTA (JP): Governor Surjadi Soedirdja wants the administration to develop an underground map of the capital before subterranean development projects begin.

Once the planned subway project and underground shopping centers are completed, Jakarta would have an underground city, he said yesterday.

"So, underground mapping is badly needed by the city to prepare the necessary regulations, to anticipate underground developments and to prevent further conflicts in the future," Surjadi said after a meeting at City Hall.

Poor planning of underground projects could cause serious problems because such areas will play an important role in the future due to the scarcity of land on which to build, he said.

Other big cities overseas, such as Singapore, have already developed below ground level, for mass rapid transportation networks and shopping centers, he said.

"The efforts have been made due to the limited land available on the surface," Surjadi said.

According to the head of the city's Mapping and Land Measurement Agency, Mochammad Sidarta, underground mapping is an important way to identify the geology of the land before beginning construction.

"Based on underground mapping, the administration can determine kind of projects should be allowed in which areas," Sidarta said.

He, therefore, urged the administration to complete the city's underground mapping before starting the construction of the proposed US$2.3 billion subway.

"With underground mapping, we'll find out whether the planned routes for the subway project are possible to construct," Sidarta said.

The project is scheduled to run from Blok M shopping area in the south to Kota railway station in the north, passing streets which are home to dozens of skyscrapers.

Deputy Governor of Economic and Development Affairs Tb.M. Rais said Thursday that underground mapping could also be used to preserve the city's groundwater and reduce the use of deep and artesian wells.

"Uncontrolled use of artesian and deep wells could leave holes in the ground which would eventually lead to salt water intrusion."

He said that the administration had asked government topographers to form a team to collect information and data to determine which areas' artesian wells might soon run dry.

"The city should start controlling the use of groundwater to protect the environment," Rais said.

Once the underground mapping completed, he said, the city was also planning to conduct a sea map, starting with Jakarta bay.

Data from the city's mining agency shows that one third of the city's groundwater, particularly in North Jakarta, is of the poorest quality.

Areas in which water quality is particularly low include Cilincing, Kapuk, Muara Karang, Sunter, Tanjung Priok, Kelapa Gading -- all in North Jakarta; Gambir, Jatinegara, Karet, Matraman, Petamburan, Senen, Tanah Abang -- in Central Jakarta, and Pulogadung and Cakung in East Jakarta.

These areas need 250 injection wells, which could help replenish groundwater, and 30,000 ground wells. (ste/07)